AST_EXT_LIB_CHECK has several optional parameters. When an optional parameter
is left empty, [] is used to indicate this. However, this is done in the script
./configure only then, when a further parameter is not empty. For example, when
no extra libraries are needed to test the checked library, parameter 5 is not
mentioned. Except parameter 6 and higher are used, then parameter 5 must be
empty.

However, this general rule was broken
* four times for parameter 5 (extra libs) and
* three times for parameter 4 (header)
as found via the Regular Expression \[\]\). In case of parameter 5, all cases
were changed, because that happened for no reason. In case of parameter 4, an
[] improves readability actually. Therefore for parameter 4, the only case which
did not do it was changed. All this aims to create more consistency: Only do
something different if there is a reason to do so.

Change-Id: I037ef170cf1ad94497151a9ea5071a31c656cafe

The functions behind the flag and the flag itself were removed
from Asterisk 12 as incompatible with the new architecture.

Change-Id: I058493ef7a53ee290fd225bbcbb07bf46b623ccf

Remove symbols that are depreacated and replaced:
* ast_channel_datastore_alloc
* ast_channel_datastore_free
* ast_channel_cmpwhentohangup
* ast_channel_setwhentohangup
* config_text_file_save
* devstate2str
* ast_device_state_changed
* ast_device_state_changed_literal
* ast_verbose_get_by_module

Remove unused symbols:
* channelreloadreason2txt (last used in Asterisk 12).

Remove unused ast_options flags:
* AST_OPT_FLAG_END_CDR_BEFORE_H_EXTEN / ast_opt_end_cdr_before_h_exten
* AST_OPT_FLAG_VERBOSE_MODULE / ast_opt_verb_module
* AST_OPT_FLAG_INITIATED_SECONDS

Change-Id: I841255995d195f8efc1ed47af9c7a2f131c08645

* dahdi_chan_name
* dahdi_chan_name_len
* dahdi_chan_mode
* __manager_event
* dialed_interface_info

Added comment about __progname and environ being needed for FreeBSD to
prevent accidental removal in the future.

Change-Id: I3ae026bc541cd9cb572be2ffa95fc359547642b5

Change-Id: I317a82de976bbdbfe4352c243e32a7bb8f66c377

Change-Id: I140e1137906bbfcdb61c0c6304159be459ad873e

If the two formats on a channel are equal, we don't transcode and since
the generic plc needs slin to work, it doesn't get invoked.

* A new configuration option "genericplc_on_equal_codecs" was added
  to the "plc" section of codecs.conf to allow generic packet loss
  concealment even if no transcoding was originally needed.
  Transcoding via SLIN is forced in this case.

ASTERISK-27743

Change-Id: I0577026a179dea34232e63123254b4e0508378f4

Change-Id: I658141c6ec490a3e866b02d2afea757928ceaabf

Change-Id: I5133ff2ba4e030f9733fb3d050c863d72a22ae6b

Change-Id: I3775a696d6a57139fdf09651ecb786bcf1774509

* Define CHAR_T_LIBEDIT and CHAR_TO_LIBEDIT based on
  HAVE_LIBEDIT_IS_UNICODE.  This avoids needing to repeatedly use
  conditional blocks, eliminates having multiple function prototypes.
* Remove parenthesis from return values.
* Add missing code block brackets {}.
* Reduce use of 'else' conditional statements where possible.

Change-Id: I4315328ebea2f62641faf6881de2ac20a9f9d08e

Asterisk uses various symbols of the shared library libogg within the module
format_ogg_vorbis. However, the source code of that module did not include the
header file of libogg explicitly but implicitly. Because that header was not
included before Asterisk 14, the script ./configure was told not to check for
it.

Anyway, even Asterisk 13 LTS uses symbols of libogg. Therefore, that header
should be included explicitly. Therefore, ./configure should check for that
header.

Change-Id: I98c50d56311b68880d1084fcc62c35ab2f8692db